The protest, which began at midnight, comes after a string of high profile incidents at prisons, including an alleged murder, a riot and two inmates escaping.

But the Ministry of Justice claimed the industrial action was unjustified and blasted it as ‘unlawful’.

Mr Gillan said: ‘Every prison officer in England is commencing a protest outside their establishment against the disregard for health and safety of our prison officers and prisoners.’

They will provide emergency cover for fires and medical incidents in order to protect prisoners’ well-being, he said.

They will cover emergencies like fires or medical incidents (Picture: PA)

Prison officers cannot by law take part in a strike and Mr Gillan admitted the day of action will be ‘interpreted as a strike’.

A union spokesman said: ‘The POA has consistently raised the volatile and dangerous state of prisons, as chronic staff shortages and impoverished regimes has resulted in staff no longer being safe, a lack of discipline and prisoners taking control of areas.

‘The continued surge in violence and unprecedented levels of suicide and acts of self harm, coupled with the recent (alleged) murder and escapes, demonstrate that the service is in meltdown.’